Embodiments of the present invention relate to transaction management systems and, more specifically, to debugging a transaction in a replica execution environment.
The Information Management System (IMS), by International Business Machines®, is a database and transaction management system. The IMS transaction processing environment provides a control region as well as dependent regions for message processing. One type of such dependent region is a message-processing region (MPR), also referred to as an online message region. MPRs are organized into message classes, which may be used for load distribution across the MPRs, and where an MPR of a certain class serves transactions assigned to that class. The control region manages incoming transactions and assigns them to the MPRs and other dependent regions as appropriate.
In the form of messages, the control region receives transactions entered from terminals. Generally, a transaction involves executing an associated program given some input data provided at a terminal. Upon receiving a message describing a transaction, the control region queues the message. Later, when it is deemed time to handle the transaction, the control region passes the message to an MPR associated with the class of the transaction, and the MPR starts the associated program to process the input data. After the MPR completes the transaction, the control region sends a response back to the terminal as appropriate.
If one or more users are debugging transactions that have been routed to the MPRs of a specific class, that class may not have any available MPRs to dispatch other work. Because debug sessions take much longer to execute than do standard transactions, this can result in a severe degradation of the transaction scheduling environment.